Backflow-Preventer

ABSTRACT

The invention is concerned with a seal, particularly in a line which is connected to a sanitary appliance such as a shower drain and the sewer It has a passageway with a passage ( 4 ) of which a sheet like boundary ( 2 ) is easily deformable such that said passageway has a first position wherein the passage is gas tight and a second position wherein the passage allows passage of liquid. Said passage boundary biases said passage in the first position by a force. The passageway ( 2 ) is substantially sheath or hose like and the passage ( 4 ) is at the outer side thereof and the passage ( 4 ) is ring gap like and extends in flow direction (arrow A) over some distance.

The invention is concerned with a seal, particularly, but notexclusively, to connect sanitary appliances to the public sewer. Thisseal is preferably of the one way or back flow preventing type.

Although in the following the invention is described in connection withsanitary applications, it will be appreciated that the invention is alsoapplicable in other fields, e.g. to tanks or pipelines with fillopening, such as for chemicals. Another field of application is sealinga vacuum cleaner bag. The seal is not only designed for liquids, butalso for gasses and (fluid) solid materials, like granules. E.g. theseal can be assembled into a fill or dispensing opening. Location in achannel is also feasible.

Sinks, toilets, bidets, urinals, bath pools and other sanitaryappliances of households, offices, institutions, etc., connected to thepublic sewer, generally are provided with a bend filled with water(water trap), such that under all circumstances there is provided aclosure allowing passage in a single direction between the domesticspace (such as bath room) containing the sanitary appliance and thesewer. This one way valve is particularly designed to prevent bad odorsand dangerous (explosive) gasses to enter the domestic room from thesewer.

Application of a water trap has several disadvantages: as soon as thewater is removed therefrom, the correct functioning of the water trap islost. In particular urine provides inhygienic reaction products withwater (such as bad odors, urine stone), such that a water trap mustalways be flushed with water. The water trap consumes additional spaceand it does not look attractive.

Recently, one has tried to avoid a number of disadvantages of the bendfilled with water by removing the water flushing and filling the bendwith parrafin (viz. E.g. U.S. Pat. No. 5,711,037).

Another prior art solution makes use of a flexible, tapering hosethrough which the disposable material flows and of which the narrowedend prevents a back flow and can expand to let disposable materials passin the desired downstream direction (viz. e.g. EP-A-1.174.549).

Besides, alternatives are known, e.g. in ships or airplanes, wherein useis made of a pivoting, rigid valve which is kept closed by springpressure and opens when a vacuum develops at the downstream side. Such aknown system is, a.o. due to its complexity, not designed for sanitarysystems connected to the public sewer. This system can also not preventthat gasses from the sewer pass the seal when the valve is pivoted open.

According to the invention a new seal is proposed, particularly whereina liquid reservoir, e.g. filled with water or parrafin, is not requiredto maintain the desired back flow prevention. This seal is particularlysuited for a relatively large flow of exhaust materials. It is veryreliable, and also cheap and has a long life. Refer to the enclosedclaims.

If material to be disposed of (urine, bath water, etc.) is offered, theseal opens automatically. With small feed of such material, the sealopens only locally. Thus no gas, liquid etc. can pass through the sealin back flow direction.

The seal is preferably connected to the from the sanitary deviceextending (e.g. plastic or metal), preferably at least substantiallyvertical exhaust channel to the sewer or similar receipt for exhaustmaterials.

The invention, further objects and corresponding advantages, areillustrated in the following with the aid of a presently preferredembodiment shown in the drawings, which is not meant to limit theexclusive rights, and showing in:

FIG. 1-3 in sectional side view a first, second and third, respectively,embodiment, in closed position;

FIG. 4 a sectional side view of the third embodiment, in open position;

FIG. 5 a cross section of the membrane;

FIG. 6 an alternative of detail VI in FIG. 3;

FIG. 7 an exploded sectional view of a further variant of the invention;

FIG. 8 the top and bottom view of some parts of the in FIG. 7 shownvariant;

FIG. 9 a further alternative in sectional side view.

FIGS. 7 and 8 are at true scale.

The seal 1 prevents that matter passes opposite the direction of arrowA. The seal 1 contains a sheath or hose like membrane 2 concentricallywithin a substantially more rigid tube 3 (e.g. of PVC or steel), suchthat under normal circumstances the membrane circumferentially sealinglyconnects to the tube. The membrane 2 can have a closed cross section,however an open cross section is also possible, e.g. wherein the freelongitudinal edges mutually overlap in the sealing position (viz. FIG.5). The membrane 2 is preferably supple pleatable and therefor ofrelatively thin walled material, such as latex, rubber or rubbery. Itswall thickness usually measures 20% at the most of that of the tube 3.

The structure is such that with a flow in the direction of arrow A saidflow finds its way between the membrane 2 and the tube 3, wherein themembrane 2 due to its easy formability moves away from the tube 3 suchthat the seal opens automatically. The membrane 2 is so to speakcompressed by the flow, such that its diameter decreases. When the flowstops, the membrane 2 returns to its original shape and comes to restagainst the tube 3, such that the seal 1 automatically closes. Thus theflow goes external of membrane 2 and internal of tube 3, through a ringgap.

FIG. 1 shows how the tube 3 expands at its upper side, such that in thedirection of arrow A a narrowing ring gap 4 is made between tube 3 andmembrane 2, through which the flow in the direction of arrow A arrivesbetween membrane 2 and tube 3.

FIG. 2 shows how the membrane 2 narrows at its top, such that a ring gap4 with a function similar to FIG. 1 is obtained.

FIG. 3 shows how the tube 3 has transverse perforations 5 at its upperend, through which the flow in the direction of arrow A goes firstthrough the perforations 5 and then through the ring gap betweenmembrane 2 and tube 3.

FIG. 3 also shows, how the seal 1 is mounted in a recess, a.o. for aconvenient fluid exhaust. E.g. said recess 6 is present in a floor 7(e.g. of a shower) and is covered by a perforated cap 8. For ease ofmounting the tube 3 is provided with a sideways projecting stop 9, e.g.a ring flange, and can tighly fitting be inserted in the (existing)drain 10. The radial perforations 5 are above the stop 9. A closed cap11 is mounted on top of the tube 3, clamping the flange 12 of themembrane 2 with the tube 3. The cap 8 has a tube stud 13 which isclamped onto the cap 11 with a tight fit.

For a reliable operation a spacer/opener 14 is present within themembrane 2, preferably with an in the direction of the arrow A taperingshape, e.g. a cone or another rotation symmetric body. With that it isprevented that the seal remains open after the flow is stopped since theby the flow compressed hose does not automatically open by e.g. walladhesion. Preferably the spacer/opener 14 extends over at least thecomplete length of the membrane 2.

For an improved seal it is preferred that, relative to the direction ofarrow A, the diameter of the membrane 2 increases and/or the diameter ofthe tube decreases, and this preferably gently such that a (truncated)conical shape is obtained.

Advantageous dimensions (in mm) of the membrane 2 are as follows:diameter from 10, preferably from about 20; wall thickness from 0.1,preferably about 0.2; length from 5, preferably from about 10; length(preferably at least about 1.5 times) larger than diameter; diameterincrease over total length from 5%, preferably from about 10%. Thelength part of the membrane 2 bearing agiant the tube 3 and forming thering gap like axhaust channel with it, measures preferably from 5, morepreferably from about 10 mm, while of this length part the wallthickness is preferably constant (besides fabrication tolerances andnatural material shrink).

The inner wall of the tube 3 is, at least over the length part againstwhich the membrane 2 bears and with it the ring gap like exhaust channelforms, prismatic (besides fabrication tolerances and natural shrink).

The membrane 2 is preferably made of rubber, rubbery or otherelastomeric material, such as latex, silicon, neoprene, vitron, NPDM orpre-vulcanised natural latex, preferably with a low ammonium content ofnot more than 20% such as at least substantially 15%. An example of thelatter can be obtained under the trade mark LA-5. The membrane 2 can bemade by dipping (material diposition on the outer side of a mould) orinjection moulding (pouring material in a mould). The tube 3 ispreferably of non elastomeric material, and e.g. of material anddimension such as typical for drains and fittings for sanitaryapplications.

It will be appreciated that the membrane 2 and the tube 3 are rotationsymmetric. The membrane 2 is mounted without or with just slight prestress. Membrane 2 and tube 3 are at least substantially co-axial.

FIG. 6 shows of detail VI in FIG. 3 an alternative. Of tube 3 is theinner side at its lower end circumferentially displaced inward over someheight. The membrane 2 thus only circumferentially seals to the part ofthe inner side of the tube 3 over a height area. Over the further heightpart wherein membrane 2 and inner side of the tube 3 coextend, they keepa mutual ring gap 4. Thus opening of the seal in flow through directionis made easier. The wall step of the tube 3 can also be present atanother level or made different.

FIG. 7 shows an embodiment wherein, viewed in flow through direction(arrow A), the membrane 2 is downstream from its entrance sidemaintained in position relative to the tube 3 by mounting means. Thesemounting means comprise (viz. also FIG. 8) radial webs 15, with the oneend fixed to the lower edge of the tube 3 and with the other end fixedto a central shaft 16, co-axial with the tube 3, and having a wallthinning, forming a connector, at the end opposite the webs 15. The cap11 is provided with a shaft 17 of which the end opposite the cap 11 issheath like.

The tube 3 has a part with smaller outer diameter, according to theinner diameter of the exhaust tube 10 (not shown; viz. FIG. 3). Thechange to the part with smaller diameter makes a step or flange 9 suchas with the embodiment according to FIG. 3. Thus the tube 3 is onlypartly inserted into the exhaust 10.

In the mounted condition the membrane 2 is with its flange 12 mounted tothe cap 11 by a ring 18 to be clamped to the cap 11. The connectorshaped end of the shaft 16 is inserted in the sheath shaped end of theshaft 17, such that they are mutually in extension. The membrane 2 isinserted into the tube 3 beyond the wall step 19 forming the ring gap 4(viz. FIG. 6). The screw 20 is screwed into the shaft 17 and keeps thecap 11 and tube together.

Due to the length of the shafts 16 and 17 a flow through gap ismaintained between the lower side of the cap 11 and the top edge of thetube 3, that like the flow through perforations 5 of the formerembodiment allows the fluid flow in the direction of arrow A from theoutside to between the membrane 2 and tube 3.

Since, different from the embodiments of FIG. 1-6, this flow through gapis interrupted in circumferential direction of the membrane 2, upstreamfrom the circumferential sealing area where the outer wall of themembrane 2 contacts the inner wall of the tube 3 any obstruction lacksto which dirt, like hairs, can hook. Such dirt can, if it extends intothe circumferential sealing area, destroy the proper sealing of themembrane 2 and tube 3. Since such obstruction is lacking, all dirtarriving between the membrane 2 and tube 3 is reliably removed and aproper seal against fluid flow opposite the direction of arrow A issecured.

The embodiment of FIG. 7-8 is also better to select the height of theflow through gap without limitation.

Starting from the embodiment of FIG. 7-8 an embodiment based on FIG. 3can be obtained by eliminating the shaft 16, webs 15 and screw 20. Oneor more, e.g. four, axial, e.g. rod like, spacers (with mutual spacing)are present between the tube 3 and cap 11. The cap 11 e.g. bears via theclamping ring 18 onto the spacers bearing on the edge of the tube 3.Clamping ring 18, spacers and tube 3 can in that case be integrated. Thespace between the spacers determines the flow through perforations 5.The length of the spacers determines the height of the perforations 5.

The tube 3 can be e.g. integrated with the exhaust 10 or suchline/channel. E.g. starting from FIG. 3 tube 3 is then eliminated andthe diameter of membrane 2 is adapted to that of tube 10. The membrane 2can, e.g. via cap 11, be suspended from the bridging part or coveringgrate 8 bearing against the floor 7.

A further example thereof is shown in FIG. 9 (in top and sectional viewaccording to arrow C-C), wherein the, e.g. central, tube 10 does notproject above the bottom of the, e.g. elongated, drain 6. At a distanceabove the exhaust 10 a co-axial ring shaped supporting part 21 is via abridging part 22 mounted to the side walls of the shower drain 6. Theassembly of cap 11, membrane 2 and clamping ring 18 can be applied byinserting the membrane with its free end into the ring 21 and the pipe10 such that clamping ring 18 bears onto ring 21 and membrane 2sealingly connects to pipe 10 (membrane 2 is shown in phantom). Withlips 23 or other anchoring features at the ring 21, the cap 11 can befixated relative to ring 21. Thus membrane 2 is via ring 22 “floatingly”suspended within pipe 10. The drain 6 can completely drain, because thewater between the outer side of membrane 2 and inner wall of pipe 10 canflow away in the direction of arrow A. At a distance above ring 21 thedrain 6 can be covered with a grate 8 or such water draining cover.

For a reliable operation of the seal, particularly with a view tomaximalisation of the draining capacity, it is preferred that thedimension of the perforations 5 or gap, observed in the direction ofarrow A (to be understood as height dimension), is at least about 5 mm,preferably at least 7.5 mm, more preferably at least 10 mm, such asabout 15 mm. The length of the membrane 2 is e.g. about 40 mm. Testshave resulted in the following convenient ratios: height of perforations5 or gap at least about 20%, preferably at least 30%, more preferably atleast 40% or at least 50% of the diameter of membrane 2; height ofperforations 5 or gap at least about 10%, preferably at least 15%, morepreferably at least 20% or 25% of the length of the membrane 2; heigthof perforation 5 or gap at least about 5%, preferably at least 10%, morepreferably at least 15% or at least 20% of the sum of the diameter andthe length of membrane 2.

An embodiment based on one or more separate measurements of an in heredisclosed embodiment, possibly combined with one or more separatemeasurements from one or more other of the in here disclosed embodimentsbelongs also to the invention. An embodiment for which an in heredisclosed measurement is replaced by an equivalent also belongs to theinvention.

1-10. (canceled)
 11. Seal, particularly in a line which is connected toa sanitary appliance such as a shower drain and the sewer, with apassageway with a passage (4) of which a preferably sheet like boundary(2) is easily deformable such that said passageway has a first position¹wherein the passage is at least substantially fluid, particularly gastight and a second position wherein the passage allows passage of fluid,particularly liquid and wherein preferably said passage boundary biasessaid passage in the first position by a force, such as by (own)resilience or pressure difference.
 12. Seal according to claim 11, thepassageway (2) is substantially sheath or hose like and the passage (4)is at the outer side thereof and/or the passage (4) is ring gap like andextends in flow direction (arrow A) over some distance, such as over atleast 5 mm or about 10 mm.
 13. Seal according to claim 11, lowered in arecess (6) in a floor (7) and removably mounted on top of a pipe (10).14. Seal according to claim 11, wherein the fluid flows outside the one(2) and inside the other (3) boundary.
 15. Seal according to claim 11,wherein the passage (4) has a down stream narrowing.
 16. Seal accordingto claim 11, wherein the diameter of a boundary changes in flow throughdirection.
 17. Seal according to claim 11, wherein a spacer (14) extendswithin the boundary (2).
 18. Seal according to claim 11, wherein theboundary (2) is closed upstream and open downstream such that it isinflated by a back flow coming from the downstream side of the seal. 19.Seal according to claim 11, wherein it is designed such that in flowthrough direction (arrowA) flowing fluid enters the seal sideways orsubstantially radially and exits the seal substantially axially. 20.Seal according to claim 11, wherein the one boundary (2) extends beyondthe other (3) and possibly is made of elastomere, such as latex orrubbery.